Messages in this thread | | | Date | Tue, 14 Sep 2010 08:10:21 +0900 | Subject | Re: [PATCH 0/9] Reduce latencies and improve overall reclaim efficiency v1 | From | Minchan Kim <> |
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On Mon, Sep 6, 2010 at 7:47 PM, Mel Gorman <mel@csn.ul.ie> wrote:
<snip>
> > These are just the raw figures taken from /proc/vmstat. It's a rough measure > of reclaim activity. Note that allocstall counts are higher because we > are entering direct reclaim more often as a result of not sleeping in > congestion. In itself, it's not necessarily a bad thing. It's easier to > get a view of what happened from the vmscan tracepoint report. > > FTrace Reclaim Statistics: vmscan > micro-traceonly-v1r5-micromicro-nocongest-v1r5-micromicro-lowlumpy-v1r5-micromicro-nodirect-v1r5-micro > traceonly-v1r5 nocongest-v1r5 lowlumpy-v1r5 nodirect-v1r5 > Direct reclaims 152 941 967 729 > Direct reclaim pages scanned 507377 1404350 1332420 1450213 > Direct reclaim pages reclaimed 10968 72042 77186 41097 > Direct reclaim write file async I/O 0 0 0 0 > Direct reclaim write anon async I/O 0 0 0 0 > Direct reclaim write file sync I/O 0 0 0 0 > Direct reclaim write anon sync I/O 0 0 0 0 > Wake kswapd requests 127195 241025 254825 188846 > Kswapd wakeups 6 1 1 1 > Kswapd pages scanned 4210101 3345122 3427915 3306356 > Kswapd pages reclaimed 2228073 2165721 2143876 2194611 > Kswapd reclaim write file async I/O 0 0 0 0 > Kswapd reclaim write anon async I/O 0 0 0 0 > Kswapd reclaim write file sync I/O 0 0 0 0 > Kswapd reclaim write anon sync I/O 0 0 0 0 > Time stalled direct reclaim (seconds) 7.60 3.03 3.24 3.43 > Time kswapd awake (seconds) 12.46 9.46 9.56 9.40 > > Total pages scanned 4717478 4749472 4760335 4756569 > Total pages reclaimed 2239041 2237763 2221062 2235708 > %age total pages scanned/reclaimed 47.46% 47.12% 46.66% 47.00% > %age total pages scanned/written 0.00% 0.00% 0.00% 0.00% > %age file pages scanned/written 0.00% 0.00% 0.00% 0.00% > Percentage Time Spent Direct Reclaim 43.80% 21.38% 22.34% 23.46% > Percentage Time kswapd Awake 79.92% 79.56% 79.20% 80.48%
There is a nitpick about stalled reclaim time. For example, In direct reclaim
=== trace_mm_vmscan_direct_reclaim_begin(order, sc.may_writepage, gfp_mask);
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); ===
In this case, Isn't this time accumulated value? My point is following as.
Process A Process B direct reclaim begin do_try_to_free_pages cond_resched
direct reclaim begin
do_try_to_free_pages
direct reclaim end direct reclaim end
So A's result includes B's time so total stall time would be bigger than real.
-- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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